The overall objective of our research program continues to be the development of new methods for the construction of novel heterocyclic systems. The use of dipolar cycloaddition chemistry for the synthesis of alkaloids will be explored. Several of the parent alkaloids we intend to synthesize display antimitotic action and are believed to function as bis alkylating agents in rendering cells incapable of cell division. Our goals include (1) and investigation of the fluoride induced desilylation of a series of Alpha-aminosilylnitriles and related compounds as a method of generating azomethine-ylides (2) a program of study using the vinyl azomethineylide 1,5-electrocyclization reaction to synthesize several pyrrolizidine alkaloids (3) intramolecular dipolar cycloadditions of several nitrilium betaines will be studied and this methodology will be used to synthesize ptilocaulin, a known cytotoxic alkaloid (4) an investigation of vinyl triazolines as a method for the formal intramolecular delivery of a nitrene to a 1,3-diene and (5) the Lewis acid catalyzed dipolar cycloadditions of chelating bidentate nitrones will be studied. Many of the substances to be synthesized are expected to show interesting malignant growth inhibiting properties and will be tested at the National Cancer Chemotherapy Service Center.